In 1923 Vittorio Siracusa was the first to use the absorption-elution technique for the ABO blood group typing of bloodstains.
At a crime scene, when there appear to be spatters of dried blood, investigators must follow a logical process in order to identify the unknown substance. The first question to be answered is whether or not the material in question is blood. Once that has been established, it is necessary to determine whether the blood sample originated from an animal. When the unknown sample has been conclusively identified as a sample of animal blood, the next question to be answered is the species of animal from which it came. Assuming that the sample is found to contain blood, that the blood emanated from an animal, and that the animal is human, the next task is to type the blood. After successfully typing the human blood, the investigator will want to try to establish the age, race, and gender of the human blood source. The object of this series of investigative queries is to accurately identify the source of the blood in an effort to tie it to a particular suspect, or to link a perpetrator and a crime, or to link a series of crimes.
The absorption-elution test, promulgated by Vittorio Siracusa, has tremendous forensic utility, because it can be used to identify old and severely dried bloodstains. When a determination has been made that a particular stain contains human blood, but the stain is extremely dry, an absorption-elution test can be conducted. A small sample scraping is taken and compatible antiserum antibodies are added to it. The sample is then heated until it reaches the temperature at which the antibody-antigen bonds are broken. Known red cells from standard blood groups are then added to fragments of the sample, in order to see what causes it to coagulate, in order to determine basic (ABO) blood group type.
By developing the absorption-elution test for use on old or exceedingly dried blood, Siracusa made a lasting contribution to the world of forensic science . In fact, his test remains in popular use in contemporary forensic science investigations.
see also Blood spatter; Blood, presumptive test; Bloodstain evidence; Microscopes.